HT68F20_10 Datasheet, PDF (21/232 Pages) Holtek Semiconductor Inc – Enhanced I/O Flash Type MCU 8-Bit MCU with EEPROM

HT68F20/HT68F30/HT68F40/HT68F50/HT68F60
HT68FU30/HT68FU40/HT68FU50/HT68FU60
ing the ORG statement. The value at this ORG
statement is ²700H² which refers to the start address of
the last page within the 2K Program Memory of the
HT68F30. The table pointer is setup here to have an ini-
tial value of ²06H². This will ensure that the first data
read from the data table will be at the Program Memory
address ²706H² or 6 locations after the start of the last
page. Note that the value for the table pointer is refer-
enced to the first address of the present page if the
²TABRD [m]² instruction is being used. The high byte of
the table data which in this case is equal to zero will be
transferred to the TBLH register automatically when the
²TABRD [m]² instruction is executed.
Because the TBLH register is a read-only register and
cannot be restored, care should be taken to ensure its
protection if both the main routine and Interrupt Service
Routine use table read instructions. If using the table
read instructions, the Interrupt Service Routines may
change the value of the TBLH and subsequently cause
errors if used again by the main routine. As a rule it is
recommended that simultaneous use of the table read
instructions should be avoided. However, in situations
where simultaneous use cannot be avoided, the inter-
rupts should be disabled prior to the execution of any
main routine table-read instructions. Note that all table
related instructions require two instruction cycles to
complete their operation.
In Circuit Programming
The provision of Flash type Program Memory provides
the user with a means of convenient and easy upgrades
and modifications to their programs on the same device.
As an additional convenience, Holtek has provided a
means of programming the microcontroller in-circuit us-
ing a 5-pin interface. This provides manufacturers with
the possibility of manufacturing their circuit boards com-
plete with a programmed or un-programmed
microcontroller, and then programming or upgrading the
program at a later stage. This enables product manufac-
turers to easily keep their manufactured products sup-
plied with the latest program releases without removal
and re-insertion of the device.
MCU Programming
Pins
PA0
PA2
RES
VDD
VSS
Function
Serial Data Input/Output
Serial Clock
Device Reset
Power Supply
Ground
The Program Memory and EEPROM data memory can
both be programmed serially in-circuit using this 5-wire
interface. Data is downloaded and uploaded serially on
a single pin with an additional line for the clock. Two ad-
ditional lines are required for the power supply and one
line for the reset. The technical details regarding the
in-circuit programming of the devices are beyond the
scope of this document and will be supplied in supple-
mentary literature.
During the programming process the RES pin will be
held low by the programmer disabling the normal opera-
tion of the microcontroller and taking control of the PA0
and PA2 I/O pins for data and clock programming pur-
poses. The user must there take care to ensure that no
other outputs are connected to these two pins.
· _{Table Read Program Example}
tempreg1 db ? ; temporary register #1
tempreg2 db ? ; temporary register #2
:
:
mov a,06h
; initialise low table pointer - note that this address
mov tblp,a
; is referenced
mov a,07h
; initialise high table pointer
tbhp,a
:
:
tabrd tempreg1
; transfers value in table referenced by table pointer data at program
; memory address ²706H² transferred to tempreg1 and TBLH
dec tblp
; reduce value of table pointer by one
tabrd tempreg2
:
:
org 700h
; transfers value in table referenced by table pointer data at program
; memory address ²705H² transferred to tempreg2 and TBLH in this
; example the data ²1AH² is transferred to tempreg1 and data ²0FH² to
; register tempreg2
; sets initial address of program memory
dc 00Ah, 00Bh, 00Ch, 00Dh, 00Eh, 00Fh, 01Ah, 01Bh
:
:
Rev. 1.10
21
February 1, 2010